Pâtissons Gratinée (summer squash au gratin)

The best way to make this dish delicious is to treat it like art. No, really. Arranging the tomato and summer squash slices in a regular pattern actually influences not only the visual experience of the dish, but also how the flavors and textures mix. When I serve it, people assume that there are only 3 ingredients. Somehow, although the cheese and the onion and garlic are intrinsic to the flavour, it's the thyme, tomato and squash that always stand out. With some nice fresh bread, this makes for a filling late summer meal.

2 + 3 Tbsps olive oil

2 medium onions (14 oz total), thinly sliced

2 cloves garlic, minced

1¼ lbs ripe red tomatoes, cored and cut into ¼" slices

¾ lb (about 2 small) green patty pan squash or other green summer squash, cut into ¼" slices on the bias

¾ lb (about 2 small) yellow patty pan squash, yellow summer squash or golden zucchini, cut into ¼" slices on the bias

¼ cup fresh thyme leaves (loosely packed)

1 tsp coarse salt

1¼ cups freshly grated parmigiano reggiano

Freshly ground black pepper to taste

1. Sauté the onions in the oil over medium heat, stirring constantly, until golden (about 20 minutes). Add the garlic and sauté 1 to 2 minutes.
2. Spread the onions and garlic evenly in the bottom of an oiled 2 qt shallow gratin dish.
3. Heat the oven to 375°F. 
4. Put the tomato slices on a shallow plate to drain for a few minutes and then discard any collected juices. 
5. In a bowl toss the zucchini and squash slices with the second batch of olive oil, the thyme and the salt. 
6. Reserve half of the cheese for the top of the gratin. 
7. Starting at one end of the baking dish, lay a row of slightly overlapping tomato slices across the width of the dish and sprinkle with a little of the cheese, then lay a row of zucchini overlapping the tomatoes, sprinkle with cheese. Repeat, until the dish is full.
8. Season lightly with pepper. Drizzle with some more olive oil and sprinkle over the reserved cheese. 
9. Cook until well-browned all over and the juices have bubbled for a while and reduced considerably, 65 to 70 minutes. Let cool for at least 15 min. before serving.